44 
STAUROPUS FAGI. 
(Read January 7th, 1902, by A. W. MERA.) 
When I promised to read a few notes on Stauropus fagi, I was 
under the impression that I might produce a few details connected with 
the species that were not generally known, but on looking up the sub¬ 
ject a little I find that a most exhaustive paper was read at this society 
some years ago, leaving no point of interest untouched.* Under these 
circumstances, all that is left to me is to repeat, in a somewhat cur¬ 
tailed form, what has already been said, hoping that some of the 
members, like myself, have not kept in touch with all that has passed. 
I believe the late W. H. Tugwell was the first to record the fact that 
the young larvae of S. fagi eat nothing but the shell of the egg they 
have just left until after the first moult. Since that time I have bred 
them from the egg once or twice myself, and I could not detect that 
anything was eaten for that period, with the exception of the eggshell. 
It certainly seems very mysterious that a larva should exist for so long, 
and nearly double its size, on the one meal which it takes immediately 
after hatching. I remember reading that Mr. Tugwell said he watched 
his larvae most carefully, and was perfectly certain as to his observa¬ 
tion, but although I am quite sure no part of the leaf is eaten, I still 
think it possible that the larvae may obtain some nourishment from the 
hairy stalks of the young shoots of the beech. I have repeatedly seen 
the larvae resting on the new shoots of the beech, which are covered 
with what might be described as fine down, with their front legs 
moving in a manner which would suggest feeding, although nothing 
appeared to be missed from the twigs. I have not tried the experiment 
of depriving the larvae of their first meal of shell, but probably it is a 
necessary tonic. I know that with Andria ( Dicranura ) rinula it is 
necessary for the larvae to eat their cast-off skin, and when I have de¬ 
prived them of it they have invariably died. 
The larva of S. fagi is a most remarkable creature, with its long 
forelegs, and more resembles an ant than a caterpillar, and is quite 
unlike any other British larva. In confinement the larvse require 
plenty of room, as they are very much given to fighting, and very soon 
lose their front legs in the struggle. In one batch that I had, several 
lost one or more of their front legs, and although I did not keep the 
wounded ones separate, when the moths emerged I had several which 
only had stumps for their front legs, with the first joint and claw 
missing. These had great difficulty in supporting themselves in a 
position for their wings to dry. 1 am really not prepared to say 
whether the forelegs of the larva produce the legs of the moths, or 
whether the above was simply a coincidence. Mr. Hamm tells me 
that the larva has the power of ejecting a strong acid. He says, “ as 
I was once made painfully aware when I accidentally squeezed one, and 
some of the fluid went into my eye.” He also tolls me that the larva; 
* “ Notes on Stauropus fagi,” by A. F. Bayne, “ Transactions” for 1893, pp. 
4-13. 
